The invention relates to a carbon black reactor. In another aspect, the invention relates to a method for producing carbon black.
Two types of carbon black are commonly used by the rubber industry for reinforcing rubber. The first is the so-called hard carbon black which imparts high wear resistance to rubber into which it has been compounded. Hard carbon black is generally used to make vehicular tire treads. Another type of carbon black, which imparts a different set of properties to rubber, is a so-called "soft" carbon black. Soft carbon blacks are generally used to reinforce rubber where a great deal of flexing is expected to be encountered, such as in tire carcasses. Hard carbon blacks are commonly classified as being in the N100, N200, or N300 series. Some soit carbon blacks are commonly classified as being in the N500, N600, and N700 series. The processes for making soft and hard carbon blacks differ considerably.
Reactors for the production of soft carbon blacks, which are characterized by large particle size, are generally characterized by large size and attendant low velocities of reactants. Where an oil feedstock is converted to a soft carbon black by pyrolysis of the oil feedstock with hot gases, the pyrolysis reaction can be conducted in a reactor which is vertically positioned, of cylindrical configuration, and of substantially uniform diameter throughout its length.
Generally speaking, smaller particle carbon blacks, toward the hard end of the scale, are produced as reactant velocities increase. However, in a given plant, there is a limit as to the velocities which can be achieved in a given reactor. The limitation is nearly always found in the air compressors, which are incapable of moving enough air to generate high velocity in a large reactor, although they can yield high or low velocity in a small reactor. Therefore, reactors with smaller diameters frequently provide greater flexibility in product production than large reactors. On the other hand, the large reactors are desirable from the standpoint of producing large particle carbon black, for example carbon black in the N700 series, at an acceptable rate.
It would be very desirable to provide a carbon black reactor capable of the flexibility of operation which is usually associated with a smaller reactor and the product throu8hput usually associated with a larger reactor.